Investigation of the Flame-Retardant and Mechanical Properties of Bamboo Fiber-Reinforced Polypropylene Composites with Melamine Pyrophosphate and Aluminum Hypophosphite Addition

Eco-friendly flame-retardant bamboo fiber/polypropylene composite based on the immobilization of halloysite nanotubes by tannic acid-Fe3+ complex

Bamboo fibers (BF), as an important sustainable natural material, are becoming a hot alternative to synthetic fibers for the reinforcement of polypropylene (PP)-based composites. However, the weak interfacial compatibility between BF and PP as matrix and their inherent flammability limit the practical application of BF/PP composites (BPC). Here, a fire-safe BPC was fabricated by constructing flame-retardant interfacial layers containing tannic acid (TA)-Fe3+ complex and halloysite nanotubes (HNTs) on the fiber matrix followed by a hot-pressing process. The results showed that the interfacial chelating of TA with Fe3+ improved the dispersion of HNTs on the fibers and the interfacial interactions within the fiber matrix, resulting in the as-fabricated composite with significantly improved mechanical properties and water resistance. In addition, the flame-retardant composite exhibited higher thermal stability and enhanced residual char content. Moreover, the composite possessed significant flame-retardant performances with a reduction of 23.75 % in the total heat release and 32.44 % in the total smoke production, respectively, owing to the flame retarding in gaseous phase and condensed phase of TA-Fe3+@HNTs layers. This work offers a green and eco-friendly strategy to address the inherent problems of BPC material in terms of fire safety and interfacial compatibility, thus broadening their applications in the automotive interior and construction industries.

A Review on Bast-Fibre-Reinforced Hybrid Composites and Their Applications

The development of eco-friendly products to protect the environment has become a topical subject in the research and industrial communities. This is a result of strict environmental regulations necessitating the development of novel strategies to reduce our reliance on petroleum-based products, which exert a negative effect on our ecosystem. Bast-fibre-based hybrids have been extensively studied for various applications due to their eco-friendliness and cost effectiveness. There is a very limited number of review articles covering the properties and preparation of bast-fibre-based hybrid composites. This review is designed to provide an overview of the preparation and application of bast-fibre-based hybrid composites. It covers the thermal properties, mechanical properties, moisture absorption and flame-retardant properties of bast hybrid composites. This review not only summarises recent advances on the use and preparation of bast hybrid composites, it also presents a future outlook.

Separator with Nitrogen-Phosphorus Flame-Retardant for LiNix Coy Mn1- x - y O2 Cathode-Based Lithium-Ion Batteries

With the pursuit of high-energy-density for lithium-ion batteries (LIBs), the hidden safety problems of batteries have gradually emerged. LiNi_x Co_y Mn_{1- x - y} O₂ (NCM) is considered as an ideal cathode material to meet the urgent needs of high-energy-density batteries. However, the oxygen precipitation reaction of NCM cathode at high temperature brings serious safety concerns. In order to promote high-safety lithium-ion batteries, herein, a new type of flame-retardant separator is prepared using flame-retardant (melamine pyrophosphate, MPP) and thermal stable Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). MPP takes the advantage of nitrogen-phosphorus synergistic effect upon the increased internal temperature of LIBs, including the dilution effect of noncombustible gas and the rapidly suppression of undesirable thermal runaway. The developed flame-retardant separators show negligible shrinkage over 200 °C and it takes only 0.54 s to extinguish the flame in the ignition test, which are much superior to commercial polyolefin separators. Moreover, pouch cells are assembled to demonstrate the application potential of PVDF-HFP/MPP separators and further verify the safety performance. It is anticipated that the separator with nitrogen-phosphorus flame-retardant can be extensively applied to various high-energy-density devices owing to simplicity and cost-effectiveness.

Experimental Investigations on Static, Dynamic, and Morphological Characteristics of Bamboo Fiber-Reinforced Polyester Composites

The use of natural fiber-reinforced polymer composites has increased over a period of time, majorly due to the ecosustainability and biodegradability of the composites. Among several grades of natural fibers, bamboo fibers offer numerous environmental and cost benefits and possess excellent mechanical characteristics. The superior properties of the bamboo fibers have triggered the research interests in the domain of bamboo fiber-reinforced polymer composites. Among the polymers, polyesters are long chain molecules made up of atoms arranged in various ways with other elements to form the basic building blocks of a polymeric chain. Polyester is being increasingly employed in today’s industrial products due to its inherent advantages. As a result, based on the potential properties of bamboo fibers as reinforcing materials and polyester resin as matrix material, the biocomposites are synthesized by hand lay-up technique and the specimens cut as per the standard dimensions and subjected to mechanical investigations, vibration, and morphological characterization as per the ASTM test methods. The increase in fiber weight content has enhanced flexural, tensile, and impact characteristics and improved the damping characteristics of the composite specimens. The microstructural evaluations have revealed the uniform distribution of the bamboo fibers in the resin, and the morphological studies of the fractured specimens have revealed that the fracture is majorly due to the matrix cracks rather than the fiber debonding, which is a major attribute ascertaining the strong coherent strengthening mechanism brought about by the inclusion of bamboo fiber in the polyester resin.

Development and Application of a New Flame-Retardant Adhesive

A new design adhesive mixed with flame retardant was developed by an optimized and modified dedicated flame retardant and selected at a suitable proportion between the adhesive and flame retardant as well as the coating amount of the adhesive. The new design adhesive was applied to ecological board production, and the flame-retardant properties of products were examined. The dipping and peeling properties, surface bonding strength, and formaldehyde emission reached the national standard GB/T 34722-2017, the flame retardancy meets the requirements of GB/T 8626-2017, GB/T 20284-2006, GB/T20285-2006, and it also reaches the B1-C level (the nonflammable level in the flame retardant level). This study not only has theoretical guidance but also has strong practical value to provide a basis and data support for the research and development of flame-retardant ecological boards.

A Review on the Flammability Properties of Carbon-Based Polymeric Composites: State-of-the-Art and Future Trends

Carbon based fillers have attracted a great deal of interest in polymer composites because of their ability to beneficially alter properties at low filler concentration, good interfacial bonding with polymer, availability in different forms, etc. The property alteration of polymer composites makes them versatile for applications in various fields, such as constructions, microelectronics, biomedical, and so on. Devastations due to building fire stress the importance of flame-retardant polymer composites, since they are directly related to human life conservation and safety. Thus, in this review, the significance of carbon-based flame-retardants for polymers is introduced. The effects of a wide variety of carbon-based material addition (such as fullerene, CNTs, graphene, graphite, and so on) on reaction-to-fire of the polymer composites are reviewed and the focus is dedicated to biochar-based reinforcements for use in flame retardant polymer composites. Additionally, the most widely used flammability measuring techniques for polymeric composites are presented. Finally, the key factors and different methods that are used for property enhancement are concluded and the scope for future work is discussed.